1. Field of the Invention
The subject matter disclosed herein relates to the use of specific exhaust temperature anomalies in multi-cylinder internal combustion engines to detect unwanted fugitive fueling.
2. Discussion of the Prior Art
As used herein, the term “fugitive fueling” means a phenomenon in which an engine receives fuel in excess of that which the engine's fuel controller intends to deliver, either by injectors or by another fuel delivery device. Fugitive fueling may occur in a variety of situations. For example, if an engine is operated in a hydrocarbon contaminated atmosphere, such as could occur in the event of a spill at a petroleum transfer terminal or a recycling facility, sufficient unwanted, or fugitive, hydrocarbons may be inducted by the engine's air system to cause overspeed and severe engine damage. A mishap such as vehicular accident or train wreck may create fugitive fueling situations as well.
Another type of fugitive fueling may occur due to a leak in an engine lubrication system. Such leaks may occur in a turbocharger or other component connected with the engine's air inlet system. Those skilled in the art will appreciate that engines, particularly diesel engines, are capable of operating quite well on lubricating oil, including lubricating oil aspirated into the engine's cylinders as a result of failure in a component such as a turbocharger bearing, or a failure such as the dropping of a cylinder poppet valve. In any case, fugitive fueling may provide hundreds of horsepower worth of fuel to a large engine which is sufficient to cause the engine to overspeed if the engine is unloaded.
Known systems and methods monitor engine speed and attempt to limit overspeeding by controlling fuel delivery. This method of control may not be effective in the case of engines which exhibit overspeeding only after a significant time has passed since the onset of a fugitive fueling event, because the passage of time frequently allows a large quantity of lubricating oil to build up improperly within a location accessible to the engine's air inlet system. Once this occurs, fuel limiting may not be sufficient to prevent a damaging overspeed event.
A need exists for a system and method to detect and respond to fugitive fueling before an engine overspeeds, and indeed, prior to the build-up of lubricating oil which could cause a deleterious overspeed event.